. The anatomy of the domestic fowl . Domestic animals; Veterinary medicine; Poultry. THE URO-GENITAL SYSTEM l8l The shell membrane consists of two layers, an inner delicate, and an outer thicker layer. When the egg is just laid these two membranes are in all parts closely adherent to each other, and the egg content completely fills the shell cavity. As soon as the content cools there is a slight contraction; the two shell membranes separate at the large end of the egg, forming an air cell which gradually enlarges as the evaporation of Uqvdd through the pores of the shell takes place. The shell
. The anatomy of the domestic fowl . Domestic animals; Veterinary medicine; Poultry. THE URO-GENITAL SYSTEM l8l The shell membrane consists of two layers, an inner delicate, and an outer thicker layer. When the egg is just laid these two membranes are in all parts closely adherent to each other, and the egg content completely fills the shell cavity. As soon as the content cools there is a slight contraction; the two shell membranes separate at the large end of the egg, forming an air cell which gradually enlarges as the evaporation of Uqvdd through the pores of the shell takes place. The shell consists of several layers. Three are easily distinguish- able: first, an inner mammUlary layer, consisting of minute conical. Fig. s8.—A diagram of the parts of the egg. a. The blastoderm, b. The shell, c. The outer shell membrane, d. The inner shell membrane, e, The air- sac at the large end of the egg. /, The albumin, g. The chalaza. h. The yellow layers of yolk, i, The white layers of yolk, k, The £ask-shaped portion of white yolk. I, The vitelline membrane. deposits of calcareous material; second, a middle spongy layer, composed of a thick network of fibers; third, an outer deUcate, cuticle-like structure. In certain breeds of poultry a pigment may be added; for example, in ducks a pea green, in txurkeys a spotted brownish material, and in fowls pink and various shades of brown. The egg shell is porous to admit the free exchange of air during the process of incubation. An average sized hen egg weighs about 2 ounces, of which 11 per cent, is shell, 32 per cent, yolk, and 57 per cent, white. The principal chemical constituents of the egg are as follows: ash, or mineral matter, 9 per cent.; fat, or hydrocarbon, per cent.; proteids, or nitrogenous matter, per cent.; and water, Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not pe
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishe, booksubjectpoultry
